1. Field of the Invention
The present invention concerns a semiconductor flattening and polishing device which can be applied to processes for manufacturing semiconductor devices such as ultra-high-density integrated circuits (ULSIs), and more specifically, it concerns a protocol for exchanging polishing pad components in such a flattening and polishing operation.
2. Description of the Background
There are known polishing devices wherein wafers are polished or CMP-polished by using a polishing pad component which is axially supported on a spindle axle and by pressing a wafer which is retained by a chuck from above while a polishing material slurry is fed onto its pad plane and while the pad and wafer are rotated concurrently or countercurrently (see Japanese Patent Application Publication No. Kokai Hei 6[1994]-21028, Hei 7[1995]-266219, Hei 8[1996]-192353, and Hei 8[1996]-293477).
Hard foamy urethane sheets, polyester fiber non-woven cloths, felts, polyvinyl alcohol fiber non-woven cloths, nylon fiber non-woven cloths, and ones obtained by flowing foamable urethane resin solutions on these non-woven cloths and by subsequently foaming and curing them are used as pads (polishers) to be integrated with such polishing devices.
When a wafer is polished by using any of the aforementioned polishing devices, its pad becomes worn as a result of polishing, and therefore, the pad is subjected to dressing and washing operations by using a pad conditioning device after one or multiple wafers have been polished for the purpose of roughening (repairing) the pad. Concrete examples of heretofore proposed pad conditioning devices which serve such pad roughening functions include the combination of a dressing disc and a washing solution, high-pressure washing solution spray nozzles (see Japanese Patent Application Publication No. Kokai Hei 3[1991]-10769, Hei 10[1998]-202502, Hei 10[1998]-235549, and Hei 10[1998]-244459), combination of a dressing disc and a washing brush (see Japanese Patent Application Publication No. Kokai Hei 10[1998]-244458), and the combination of a cup hold-type dressing whetstone, a compressive washing solution spray nozzle, and a washing brush (see Japanese Patent Application Publication No. Kokai Hei 10[1998]-244458).
Polishing pad components are thus conditioned repeatedly, and once a polishing pad component reaches its wear limit, it is exchanged with a new polishing pad component. Such a polishing pad component is obtained by pasting a polishing cloth or polyurethane sheet (referred to as a xe2x80x9cpad,xe2x80x9d xe2x80x9cpolishing cloth,xe2x80x9d or xe2x80x9cpolisherxe2x80x9d) onto an aluminum or stainless steel attachment panel (polisher supporter), and such a polishing cloth is reloaded manually by an operator. The peeling of the polishing cloth and its pasting onto the attachment panel, however, are cumbersome during such a polishing cloth reloading operation, and furthermore, advanced skills are required, as a result of which the utilization efficiency of the polishing device decreases. It is in such a context that this method is replaced by one wherein a new polishing pad component which has been obtained by preliminarily pasting an unused polishing cloth onto an attachment panel is prepared and wherein a used and worn polishing pad component is exchanged with this new polishing pad component.
Even in such a method, however, a manual operation wherein a worker enters the polishing device in person is unavoidable, and cumbersome bolt attachment and detachment procedures are required for exchanging polishing pad components. It is in such a context that devices for automatically exchanging polishing pad components have been proposed, for example, by Japanese Patent Application Publication No. Kokai Hei 8[1996]-174406 and Hei 10[1998]-230449. In such a case, however, a polishing pad component is above a disc, the diameter of which is large and wherein a wafer, the plane of which to be polished faces downward, is polished while said wafer is pressed from above onto the pad plane of the polishing pad component. For this reason, the diameter of the disc (as well as of the polishing pad component) is large in comparison with the wafer diameter, as a result of which the structure of the automatic exchange device for exchanging such large polishing pad components becomes large and complicated, accompanied by high production costs.
Regarding the polishing devices mentioned in the aforementioned patent publications (CMP devices), furthermore, the planes of wafers to be polished face downward, and therefore the end point of the polishing operation may be estimated by decoding the variations of voltages or currents for rotating and driving the polishing pad component, wafer, etc., or the end point of the polishing operation may alternatively be estimated by configuring a laser beam transmission window on a disc and by monitoring the wafer polishing state while a laser beam is irradiated onto the plane of the wafer to be polished which is polished (see Japanese Patent Application Publication No. Kokai Hei 6[1994]-216095, Hei 8[1996]-172118, Hei 9[1997]-262743, and Hei 10[1998]-199951).
In contrast with these CMP devices, a CMP device wherein a wafer, the plane of which to be polished faces upward, is retained by the suction of a wafer chuck mechanism on an index table, wherein a polishing pad component which is axially supported on a spindle axle which is positioned above the wafer is pressed onto the wafer from above while its pad plane faces downward, and wherein the wafer is polished by rotating said wafer and polishing pad component has been proposed and put to practical uses (see Japanese Patent Application Publication No. Kokai Hei 10[1998]-303152 and Hei 11[1999]-156711). The polishing pad diameter of such a CMP device is small in comparison with the wafer diameter, and since the plane to be polished faces upward, it is easy to measure the film thickness during the polishing operation or to judge the end of the polishing operation. Since the diameter of the polishing pad component is smaller than those of the polishing pad components of the known CMP devices, furthermore, the exchange operation can be advantageously facilitated.
Such a CMP device wherein the polisher diameter is small in comparison with the wafer diameter, however, is characterized by a high utilization efficiency of the polishing plane (pad plane) of the polisher (polishing pad component), and accordingly, the depressions of the polishing plane of the polisher tend to become congested. It is necessary to increase the dressing frequency of such a CMP device for the purpose of maintaining the required polishing performances, but since the dressing is synonymous with the shaving of the polisher surface, the life of the polisher itself becomes shortened, as a result of which the period between operations for exchanging polishing pad components become shorter, and the exchange frequency increases. As has been mentioned above, furthermore, the polishing pad component is attached to the spindle axle while its pad plane faces downward, as a result of which it becomes difficult to achieve a favorable precision during the exchange operation, and the operative efficiency is problematically unfavorable.
An object of the present invention, which has been conceived in response to the foregoing problems, is to provide a polishing pad component exchange device and a corresponding method which are capable of automating polishing pad component exchange operations and of improving the polishing pad component exchanging operative efficiency. In order to solve the aforementioned problems, the polishing device of the present invention may, for example, be comprised of an object retention mechanism (e.g., wafer chuck mechanism of application embodiments) which retains an object to be polished (e.g., wafer of application embodiments) while its plane to be polished faces upward, a polishing pad component which possesses a polishing plane which polishes said plane to be polished while in contact with it, a pad retention mechanism (e.g., polishing head (2) of application embodiments) which retains said polishing pad component while said polishing plane faces downward, and a shift mechanism (e.g., shift mechanisms (7) and (107) of application embodiments) which enables a relative displacement of said polishing pad component in relation to said plane to be polished, and said plane to be polished is constituted to be polished based on the relative displacement of said polishing pad component while it is in contact with said plane to be polished. Such a polishing device, furthermore, possesses a fixation and retention mechanism which fixes and retains said polishing pad component in a detachable fashion while said polishing plane faces downward at the lower end of the polishing head, wherein the displacement distance of said shift mechanism ranges at least from the polishing position of said plane to be polished to the exchange position of said polishing pad component, and said polishing pad component is automatically exchanged while attached to and detached from the polishing head by said fixation and retention mechanism.
Regarding this polishing device, the polished object is retained by the object retention mechanism while its plane to be polished faces upward, whereas the polishing plane of the polishing pad component which is retained by the pad retention mechanism is pressed onto the plane to be polished from above, whereas the plane to be polished is polished based on the relative shift of the two (relative rotational shift) caused by the shift mechanism. In such a case, the polishing plane of the polishing pad component is generally smaller than the plane to be polished, as a result of which the polishing frequency tends to become high. Since the polishing pad component is constituted to entail automatic attachments/detachments and exchanges in relation to the pad retention mechanism using the fixation and retention mechanism and the shift mechanism which enable a shift to the polishing pad component exchange position, a used polishing pad component can be automatically exchanged with a new polishing pad component, so that the polishing pad exchanging operative efficiency can be improved.
The polishing device of the present invention is alternatively constituted by an object retention mechanism which retains a polished object while its plane to be polished faces upward, a polishing pad component which possesses a polishing plane which polishes said plane to be polished while in contact with it, a pad retention mechanism which retains said polishing pad component while said polishing plane faces downward, a shift mechanism which enables a relative displacement of said polishing pad component in relation to said plane to be polished, and a transportation mechanism (e.g., polishing pad transportation robot (18) of application embodiments) which exchanges said polishing pad component while it is transported in relation to said pad retention mechanism, and said plane to be polished is constituted to be polished based on the relative displacement of said polishing pad component while it is in contact with said plane to be polished. Regarding this polishing device, furthermore, a fixation and retention mechanism which fixes and retains said polishing pad component in a detachable fashion while said plane to be polished faces downward is at the lower end of the polishing head, wherein the pad retention mechanism is shifted to the polishing pad exchange position by the shift mechanism, so that said polishing pad component, which is transported by said transportation mechanism, is automatically exchanged while attached to and detached from said polishing head by said fixation and retention mechanism.
Based on such a constitution of the exchange device, the polishing pad component is constituted to be automatically exchanged while attached to and detached from said polishing head by said fixation and retention mechanism, and therefore, a used polishing pad component can simply be exchanged with a new one automatically. Additional automating benefits can, furthermore, be obtained based on the transportation of the polishing device, which has been thus attached and/or detached, by the transportation mechanism, based on which the exchanging operative efficiency can be phenomenally improved.
Incidentally, regarding the aforementioned invention, it is desirable for the transportation mechanism to possess an arm which is capable of gripping the polishing pad component at its front end. In such a case, the polishing pad component which is gripped by the arm component is transported to the lower end of the pad retention mechanism during an operation for attaching the polishing pad component to the polishing head, and the polishing pad component is fixed to and retained by the fixation and retention mechanism, based on which the automatic attachment of the polishing pad component can be simplified.
Regarding the foregoing constitution, a temporary binding mechanism temporarily binds the polishing pad component to the polishing head when the fixation and retention mechanism is inoperative. In such a case, the polishing pad component can be caused by the temporary binding mechanism to be temporarily bound to and supported by the polishing head.
The aforementioned polishing pad component may be constituted by a polisher which polishes said plane of the object to be polished while in contact with it and a polisher supporter which retains said polisher planewise. In such a case, the polishing pad component can be easily renewed by simply peeling the polisher from the polisher supporter and pasting a new polisher onto it with regard to a used polishing pad component which has been detached from the pad retention mechanism.
Incidentally, the fixation and retention mechanism may be constituted to induce the fixation and retention of the polishing pad component to and by the lower end of the polishing head based on vacuum suction. Moreover, the polishing pad component may be constituted by a polisher and a polisher supporter while said polisher supporter is constituted by a magnet in such a way that the fixation and retention mechanism will cause the fixation and retention of the polishing pad component to and by the lower end of the polishing head based on a magnetic force. The polishing pad component may, furthermore, be constituted to induce the fixation and retention of the polishing pad component to and by the lower end of the polishing head via a fixation mechanism (e.g., clamp mechanism, bolt stopper mechanism, etc.). The polishing pad components can be automatically exchanged with ease based on any of these constitutions.
The polishing device thus constituted may also possess a storage shelf which stores the polishing pad component, which is exchanged while attached to and/or detached from the polishing head, after it has been transported by said transportation mechanism. In such a case, multiple polishing pad components can be stored on the storage shelf, based on which the exchanging operative efficiency can be further improved.
The aforementioned polishing device may also be constituted to possess a polisher reloading mechanism which automatically peels said polisher from said polisher supporter and which automatically pastes a new polisher onto said polisher supporter in relation to said polishing pad component, which, after having been used, has been detached from the polishing head for exchange purposes. When the polisher is thus reloaded automatically, the polishing pad component exchanging operative efficiency can be farther upgraded.
Incidentally, the transportation mechanism may in this case be constituted not only to transport the polishing pad component, which, after having been used, has been detached from said pad retention mechanism for exchange purposes, to said polisher reloading mechanism but also to transport said polishing pad component the polisher of which has been reloaded by said polisher reloading mechanism onto said storage shelf. In such a case, the entire exchanging operation can be smoothly carried out.
The method of the present invention for exchanging polishing pad components, on the other hand, is constituted to utilize the polishing device of the present invention described above for exchanging polishing pad components in relation to the pad retention mechanism. If this method is implemented, the polishing pad component exchanging operative efficiency can be improved.
Incidentally, an alternative polishing device of the present invention possesses a polishing pad component which has been obtained by pasting a polisher to the rear plane of a polisher supporter which possesses a annular channel on its outer circumference and which possesses an interlocking unit which serves a positioning function on its rear plane, a head which is axially supported on a spindle axle which possesses an axial core along the perpendicular direction and which is capable of drawing said polishing pad component based on vacuum suction, an (un)lift mechanism for said spindle axle, a shift mechanism which is capable of inducing reciprocal displacements of said spindle axle between left and right and which is capable of inducing the shift of said spindle axle to the exchange position for said polishing pad, a transportation robot which is positioned along the extension of the shift orbit of the central point of said polishing pad component, which has been attached to the head of said spindle axle, between left and right, which induces the detachment of the polishing pad component from the transported spindle axle via an arm, which induces the importation of the polishing pad component onto a storage shelf or the exportation of the polishing pad component from said storage shelf based on a rotating action, and which induces the importation of the polishing pad component onto the head of the spindle axle based on another rotating action, and said storage shelf, while a gap is secured between itself and the rotation axis of said transportation robot and which can be reciprocally displaced forward and backward.
In an alternative method of the present invention for exchanging polishing pad components, furthermore, a polishing pad component which has been obtained by pasting a polisher to the rear plane of a polisher supporter which possesses a annular channel on its outer circumference and which possesses an interlocking unit which serves a positioning function on its rear plane is attached to and/or detached from a head which is axially supported on a spindle axle by using the aforementioned device for exchanging a polishing pad component based on the following processes (1) through (12):
(1): One whereby the arm of the transportation robot is elevated to the polishing pad component detachment height position vis-à-vis the head and whereby said arm is subsequently rotated by 90 along the head direction,
(2): One whereby a polishing pad component which is drawn toward the spindle axle, which possesses an axial core along the perpendicular direction, based on vacuum suction is displaced to the side of said transportation robot, which is positioned along the extension of the shift orbit of the central point of said polishing pad component between left and right, by said shift mechanism and then caused to stop at the exchange position,
(3): One whereby two pairs of rolls which have been attached to the arm of said transportation robot based on the contraction of the claw width of said arm are inserted into annular channels on the outer circumference of a polishing pad component attachment panel for the purpose of gripping the polishing pad component,
(4): One whereby the vacuum suction of the head is subsequently cancelled and whereby the detachment of the polishing pad component from the head is facilitated by feeding compressed air into said head,
(5): One whereby the arm of the transportation robot is rotated by 90 in the opposite direction and whereby said arm is subsequently elevated or lowered to a position corresponding to the height of the platform of the storage shelf on which the polishing pad component is mounted,
(6): One whereby the storage shelf is caused to move forward toward the transportation robot side and whereby the polishing pad component is mounted on the platform of the storage shelf based on the expansion of the claw width of the arm of the transportation robot,
(7): One whereby the storage shelf is caused to recede,
(8): One whereby the arm of the transportation robot is elevated or lowered to a position corresponding to a height at which a new polishing pad component can be gripped,
(9): One whereby said storage shelf is caused to move forward toward the transportation robot and whereby the two pairs of rolls which have been attached to the arm of said transportation robot are inserted into annular channels on the outer circumference of a new polishing pad component attachment panel based on the contraction of the claw width of said arm for the purpose of gripping the polishing pad component,
(10): One whereby the storage shelf is caused to recede,
(11): One whereby the arm of the transportation robot is rotated by 90 along the head direction and whereby the polishing pad component is subsequently drawn toward the head based on the vacuum suction of said head,
(12): One whereby the claw width of the arm of the transportation robot is expanded and whereby the spindle axle is caused to shift between left and right away from said transportation robot, and
(13): One whereby, when the prevailing polishing pad component becomes worn and where said polishing pad component must be exchanged with a new polishing pad component, the aforementioned processes of (2) through (12) are repeated.